Robotic ray swims rings around propeller craft

As it glides sedately beneath the waves, the ray’s languid grace belies a stunning capacity for underwater manoeuvres. With a flap of its wings, Aqua ray can swim upside down, loop the loop, hover or turn on a dime.

As agile as a real manta ray, the rubbery, robotic acrobat (pictured right) is the handiwork of Rudolf Bannasch and Leif Kniese of bio-inspiration firm EvoLogics in Berlin, Germany, and could kick-start a new generation of autonomous underwater vehicles.

Over the last decade AUVs, which are mostly propeller-driven, have been probing the oceans’ vast depths without the need for human pilots. But although they can be customised for either fine manoeuvring or long-distance cruising, only rarely can they do both.

Enter battery-powered Aqua Ray&colon; its wingspan of 1.5 metres gives it both propulsion and fine-motion control. The key to the wings’ agility lies with Finray, a technology that mimics a fish tail. An avid fisherman, Kniese noticed

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